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1# SPDX-License-Identifier: GPL-2.0
2
3config EARLY_PRINTK_USB
4 bool
5
6config X86_VERBOSE_BOOTUP
7 bool "Enable verbose x86 bootup info messages"
8 default y
9 help
10 Enables the informational output from the decompression stage
11 (e.g. bzImage) of the boot. If you disable this you will still
12 see errors. Disable this if you want silent bootup.
13
14config EARLY_PRINTK
15 bool "Early printk" if EXPERT
16 default y
17 help
18 Write kernel log output directly into the VGA buffer or to a serial
19 port.
20
21 This is useful for kernel debugging when your machine crashes very
22 early before the console code is initialized. For normal operation
23 it is not recommended because it looks ugly and doesn't cooperate
24 with klogd/syslogd or the X server. You should normally say N here,
25 unless you want to debug such a crash.
26
27config EARLY_PRINTK_DBGP
28 bool "Early printk via EHCI debug port"
29 depends on EARLY_PRINTK && PCI
30 select EARLY_PRINTK_USB
31 help
32 Write kernel log output directly into the EHCI debug port.
33
34 This is useful for kernel debugging when your machine crashes very
35 early before the console code is initialized. For normal operation
36 it is not recommended because it looks ugly and doesn't cooperate
37 with klogd/syslogd or the X server. You should normally say N here,
38 unless you want to debug such a crash. You need usb debug device.
39
40config EARLY_PRINTK_USB_XDBC
41 bool "Early printk via the xHCI debug port"
42 depends on EARLY_PRINTK && PCI
43 select EARLY_PRINTK_USB
44 help
45 Write kernel log output directly into the xHCI debug port.
46
47 One use for this feature is kernel debugging, for example when your
48 machine crashes very early before the regular console code is
49 initialized. Other uses include simpler, lockless logging instead of
50 a full-blown printk console driver + klogd.
51
52 For normal production environments this is normally not recommended,
53 because it doesn't feed events into klogd/syslogd and doesn't try to
54 print anything on the screen.
55
56 You should normally say N here, unless you want to debug early
57 crashes or need a very simple printk logging facility.
58
59config EFI_PGT_DUMP
60 bool "Dump the EFI pagetable"
61 depends on EFI
62 select PTDUMP_CORE
63 help
64 Enable this if you want to dump the EFI page table before
65 enabling virtual mode. This can be used to debug miscellaneous
66 issues with the mapping of the EFI runtime regions into that
67 table.
68
69config DEBUG_TLBFLUSH
70 bool "Set upper limit of TLB entries to flush one-by-one"
71 depends on DEBUG_KERNEL
72 help
73 X86-only for now.
74
75 This option allows the user to tune the amount of TLB entries the
76 kernel flushes one-by-one instead of doing a full TLB flush. In
77 certain situations, the former is cheaper. This is controlled by the
78 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
79 to -1, the code flushes the whole TLB unconditionally. Otherwise,
80 for positive values of it, the kernel will use single TLB entry
81 invalidating instructions according to the following formula:
82
83 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
84
85 If in doubt, say "N".
86
87config IOMMU_DEBUG
88 bool "Enable IOMMU debugging"
89 depends on GART_IOMMU && DEBUG_KERNEL
90 depends on X86_64
91 help
92 Force the IOMMU to on even when you have less than 4GB of
93 memory and add debugging code. On overflow always panic. And
94 allow to enable IOMMU leak tracing. Can be disabled at boot
95 time with iommu=noforce. This will also enable scatter gather
96 list merging. Currently not recommended for production
97 code. When you use it make sure you have a big enough
98 IOMMU/AGP aperture. Most of the options enabled by this can
99 be set more finegrained using the iommu= command line
100 options. See Documentation/arch/x86/x86_64/boot-options.rst for more
101 details.
102
103config IOMMU_LEAK
104 bool "IOMMU leak tracing"
105 depends on IOMMU_DEBUG && DMA_API_DEBUG
106 help
107 Add a simple leak tracer to the IOMMU code. This is useful when you
108 are debugging a buggy device driver that leaks IOMMU mappings.
109
110config HAVE_MMIOTRACE_SUPPORT
111 def_bool y
112
113config X86_DECODER_SELFTEST
114 bool "x86 instruction decoder selftest"
115 depends on DEBUG_KERNEL && INSTRUCTION_DECODER
116 depends on !COMPILE_TEST
117 help
118 Perform x86 instruction decoder selftests at build time.
119 This option is useful for checking the sanity of x86 instruction
120 decoder code.
121 If unsure, say "N".
122
123choice
124 prompt "IO delay type"
125 default IO_DELAY_0X80
126
127config IO_DELAY_0X80
128 bool "port 0x80 based port-IO delay [recommended]"
129 help
130 This is the traditional Linux IO delay used for in/out_p.
131 It is the most tested hence safest selection here.
132
133config IO_DELAY_0XED
134 bool "port 0xed based port-IO delay"
135 help
136 Use port 0xed as the IO delay. This frees up port 0x80 which is
137 often used as a hardware-debug port.
138
139config IO_DELAY_UDELAY
140 bool "udelay based port-IO delay"
141 help
142 Use udelay(2) as the IO delay method. This provides the delay
143 while not having any side-effect on the IO port space.
144
145config IO_DELAY_NONE
146 bool "no port-IO delay"
147 help
148 No port-IO delay. Will break on old boxes that require port-IO
149 delay for certain operations. Should work on most new machines.
150
151endchoice
152
153config DEBUG_BOOT_PARAMS
154 bool "Debug boot parameters"
155 depends on DEBUG_KERNEL
156 depends on DEBUG_FS
157 help
158 This option will cause struct boot_params to be exported via debugfs.
159
160config CPA_DEBUG
161 bool "CPA self-test code"
162 depends on DEBUG_KERNEL
163 help
164 Do change_page_attr() self-tests every 30 seconds.
165
166config DEBUG_ENTRY
167 bool "Debug low-level entry code"
168 depends on DEBUG_KERNEL
169 help
170 This option enables sanity checks in x86's low-level entry code.
171 Some of these sanity checks may slow down kernel entries and
172 exits or otherwise impact performance.
173
174 If unsure, say N.
175
176config DEBUG_NMI_SELFTEST
177 bool "NMI Selftest"
178 depends on DEBUG_KERNEL && X86_LOCAL_APIC
179 help
180 Enabling this option turns on a quick NMI selftest to verify
181 that the NMI behaves correctly.
182
183 This might help diagnose strange hangs that rely on NMI to
184 function properly.
185
186 If unsure, say N.
187
188config DEBUG_IMR_SELFTEST
189 bool "Isolated Memory Region self test"
190 depends on INTEL_IMR
191 help
192 This option enables automated sanity testing of the IMR code.
193 Some simple tests are run to verify IMR bounds checking, alignment
194 and overlapping. This option is really only useful if you are
195 debugging an IMR memory map or are modifying the IMR code and want to
196 test your changes.
197
198 If unsure say N here.
199
200config X86_DEBUG_FPU
201 bool "Debug the x86 FPU code"
202 depends on DEBUG_KERNEL
203 default y
204 help
205 If this option is enabled then there will be extra sanity
206 checks and (boot time) debug printouts added to the kernel.
207 This debugging adds some small amount of runtime overhead
208 to the kernel.
209
210 If unsure, say N.
211
212config PUNIT_ATOM_DEBUG
213 tristate "ATOM Punit debug driver"
214 depends on PCI
215 select DEBUG_FS
216 select IOSF_MBI
217 help
218 This is a debug driver, which gets the power states
219 of all Punit North Complex devices. The power states of
220 each device is exposed as part of the debugfs interface.
221 The current power state can be read from
222 /sys/kernel/debug/punit_atom/dev_power_state
223
224choice
225 prompt "Choose kernel unwinder"
226 default UNWINDER_ORC if X86_64
227 default UNWINDER_FRAME_POINTER if X86_32
228 help
229 This determines which method will be used for unwinding kernel stack
230 traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack,
231 livepatch, lockdep, and more.
232
233config UNWINDER_ORC
234 bool "ORC unwinder"
235 depends on X86_64
236 select OBJTOOL
237 help
238 This option enables the ORC (Oops Rewind Capability) unwinder for
239 unwinding kernel stack traces. It uses a custom data format which is
240 a simplified version of the DWARF Call Frame Information standard.
241
242 This unwinder is more accurate across interrupt entry frames than the
243 frame pointer unwinder. It also enables a 5-10% performance
244 improvement across the entire kernel compared to frame pointers.
245
246 Enabling this option will increase the kernel's runtime memory usage
247 by roughly 2-4MB, depending on your kernel config.
248
249config UNWINDER_FRAME_POINTER
250 bool "Frame pointer unwinder"
251 select ARCH_WANT_FRAME_POINTERS
252 select FRAME_POINTER
253 help
254 This option enables the frame pointer unwinder for unwinding kernel
255 stack traces.
256
257 The unwinder itself is fast and it uses less RAM than the ORC
258 unwinder, but the kernel text size will grow by ~3% and the kernel's
259 overall performance will degrade by roughly 5-10%.
260
261config UNWINDER_GUESS
262 bool "Guess unwinder"
263 depends on EXPERT
264 depends on !STACKDEPOT
265 help
266 This option enables the "guess" unwinder for unwinding kernel stack
267 traces. It scans the stack and reports every kernel text address it
268 finds. Some of the addresses it reports may be incorrect.
269
270 While this option often produces false positives, it can still be
271 useful in many cases. Unlike the other unwinders, it has no runtime
272 overhead.
273
274endchoice
1# SPDX-License-Identifier: GPL-2.0
2menu "Kernel hacking"
3
4config TRACE_IRQFLAGS_SUPPORT
5 def_bool y
6
7source "lib/Kconfig.debug"
8
9config EARLY_PRINTK_USB
10 bool
11
12config X86_VERBOSE_BOOTUP
13 bool "Enable verbose x86 bootup info messages"
14 default y
15 ---help---
16 Enables the informational output from the decompression stage
17 (e.g. bzImage) of the boot. If you disable this you will still
18 see errors. Disable this if you want silent bootup.
19
20config EARLY_PRINTK
21 bool "Early printk" if EXPERT
22 default y
23 ---help---
24 Write kernel log output directly into the VGA buffer or to a serial
25 port.
26
27 This is useful for kernel debugging when your machine crashes very
28 early before the console code is initialized. For normal operation
29 it is not recommended because it looks ugly and doesn't cooperate
30 with klogd/syslogd or the X server. You should normally say N here,
31 unless you want to debug such a crash.
32
33config EARLY_PRINTK_DBGP
34 bool "Early printk via EHCI debug port"
35 depends on EARLY_PRINTK && PCI
36 select EARLY_PRINTK_USB
37 ---help---
38 Write kernel log output directly into the EHCI debug port.
39
40 This is useful for kernel debugging when your machine crashes very
41 early before the console code is initialized. For normal operation
42 it is not recommended because it looks ugly and doesn't cooperate
43 with klogd/syslogd or the X server. You should normally say N here,
44 unless you want to debug such a crash. You need usb debug device.
45
46config EARLY_PRINTK_EFI
47 bool "Early printk via the EFI framebuffer"
48 depends on EFI && EARLY_PRINTK
49 select FONT_SUPPORT
50 ---help---
51 Write kernel log output directly into the EFI framebuffer.
52
53 This is useful for kernel debugging when your machine crashes very
54 early before the console code is initialized.
55
56config EARLY_PRINTK_USB_XDBC
57 bool "Early printk via the xHCI debug port"
58 depends on EARLY_PRINTK && PCI
59 select EARLY_PRINTK_USB
60 ---help---
61 Write kernel log output directly into the xHCI debug port.
62
63 One use for this feature is kernel debugging, for example when your
64 machine crashes very early before the regular console code is
65 initialized. Other uses include simpler, lockless logging instead of
66 a full-blown printk console driver + klogd.
67
68 For normal production environments this is normally not recommended,
69 because it doesn't feed events into klogd/syslogd and doesn't try to
70 print anything on the screen.
71
72 You should normally say N here, unless you want to debug early
73 crashes or need a very simple printk logging facility.
74
75config X86_PTDUMP_CORE
76 def_bool n
77
78config X86_PTDUMP
79 tristate "Export kernel pagetable layout to userspace via debugfs"
80 depends on DEBUG_KERNEL
81 select DEBUG_FS
82 select X86_PTDUMP_CORE
83 ---help---
84 Say Y here if you want to show the kernel pagetable layout in a
85 debugfs file. This information is only useful for kernel developers
86 who are working in architecture specific areas of the kernel.
87 It is probably not a good idea to enable this feature in a production
88 kernel.
89 If in doubt, say "N"
90
91config EFI_PGT_DUMP
92 bool "Dump the EFI pagetable"
93 depends on EFI
94 select X86_PTDUMP_CORE
95 ---help---
96 Enable this if you want to dump the EFI page table before
97 enabling virtual mode. This can be used to debug miscellaneous
98 issues with the mapping of the EFI runtime regions into that
99 table.
100
101config DEBUG_WX
102 bool "Warn on W+X mappings at boot"
103 select X86_PTDUMP_CORE
104 ---help---
105 Generate a warning if any W+X mappings are found at boot.
106
107 This is useful for discovering cases where the kernel is leaving
108 W+X mappings after applying NX, as such mappings are a security risk.
109
110 Look for a message in dmesg output like this:
111
112 x86/mm: Checked W+X mappings: passed, no W+X pages found.
113
114 or like this, if the check failed:
115
116 x86/mm: Checked W+X mappings: FAILED, <N> W+X pages found.
117
118 Note that even if the check fails, your kernel is possibly
119 still fine, as W+X mappings are not a security hole in
120 themselves, what they do is that they make the exploitation
121 of other unfixed kernel bugs easier.
122
123 There is no runtime or memory usage effect of this option
124 once the kernel has booted up - it's a one time check.
125
126 If in doubt, say "Y".
127
128config DOUBLEFAULT
129 default y
130 bool "Enable doublefault exception handler" if EXPERT
131 ---help---
132 This option allows trapping of rare doublefault exceptions that
133 would otherwise cause a system to silently reboot. Disabling this
134 option saves about 4k and might cause you much additional grey
135 hair.
136
137config DEBUG_TLBFLUSH
138 bool "Set upper limit of TLB entries to flush one-by-one"
139 depends on DEBUG_KERNEL
140 ---help---
141
142 X86-only for now.
143
144 This option allows the user to tune the amount of TLB entries the
145 kernel flushes one-by-one instead of doing a full TLB flush. In
146 certain situations, the former is cheaper. This is controlled by the
147 tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
148 to -1, the code flushes the whole TLB unconditionally. Otherwise,
149 for positive values of it, the kernel will use single TLB entry
150 invalidating instructions according to the following formula:
151
152 flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
153
154 If in doubt, say "N".
155
156config IOMMU_DEBUG
157 bool "Enable IOMMU debugging"
158 depends on GART_IOMMU && DEBUG_KERNEL
159 depends on X86_64
160 ---help---
161 Force the IOMMU to on even when you have less than 4GB of
162 memory and add debugging code. On overflow always panic. And
163 allow to enable IOMMU leak tracing. Can be disabled at boot
164 time with iommu=noforce. This will also enable scatter gather
165 list merging. Currently not recommended for production
166 code. When you use it make sure you have a big enough
167 IOMMU/AGP aperture. Most of the options enabled by this can
168 be set more finegrained using the iommu= command line
169 options. See Documentation/x86/x86_64/boot-options.txt for more
170 details.
171
172config IOMMU_LEAK
173 bool "IOMMU leak tracing"
174 depends on IOMMU_DEBUG && DMA_API_DEBUG
175 ---help---
176 Add a simple leak tracer to the IOMMU code. This is useful when you
177 are debugging a buggy device driver that leaks IOMMU mappings.
178
179config HAVE_MMIOTRACE_SUPPORT
180 def_bool y
181
182config X86_DECODER_SELFTEST
183 bool "x86 instruction decoder selftest"
184 depends on DEBUG_KERNEL && KPROBES
185 depends on !COMPILE_TEST
186 ---help---
187 Perform x86 instruction decoder selftests at build time.
188 This option is useful for checking the sanity of x86 instruction
189 decoder code.
190 If unsure, say "N".
191
192#
193# IO delay types:
194#
195
196config IO_DELAY_TYPE_0X80
197 int
198 default "0"
199
200config IO_DELAY_TYPE_0XED
201 int
202 default "1"
203
204config IO_DELAY_TYPE_UDELAY
205 int
206 default "2"
207
208config IO_DELAY_TYPE_NONE
209 int
210 default "3"
211
212choice
213 prompt "IO delay type"
214 default IO_DELAY_0X80
215
216config IO_DELAY_0X80
217 bool "port 0x80 based port-IO delay [recommended]"
218 ---help---
219 This is the traditional Linux IO delay used for in/out_p.
220 It is the most tested hence safest selection here.
221
222config IO_DELAY_0XED
223 bool "port 0xed based port-IO delay"
224 ---help---
225 Use port 0xed as the IO delay. This frees up port 0x80 which is
226 often used as a hardware-debug port.
227
228config IO_DELAY_UDELAY
229 bool "udelay based port-IO delay"
230 ---help---
231 Use udelay(2) as the IO delay method. This provides the delay
232 while not having any side-effect on the IO port space.
233
234config IO_DELAY_NONE
235 bool "no port-IO delay"
236 ---help---
237 No port-IO delay. Will break on old boxes that require port-IO
238 delay for certain operations. Should work on most new machines.
239
240endchoice
241
242if IO_DELAY_0X80
243config DEFAULT_IO_DELAY_TYPE
244 int
245 default IO_DELAY_TYPE_0X80
246endif
247
248if IO_DELAY_0XED
249config DEFAULT_IO_DELAY_TYPE
250 int
251 default IO_DELAY_TYPE_0XED
252endif
253
254if IO_DELAY_UDELAY
255config DEFAULT_IO_DELAY_TYPE
256 int
257 default IO_DELAY_TYPE_UDELAY
258endif
259
260if IO_DELAY_NONE
261config DEFAULT_IO_DELAY_TYPE
262 int
263 default IO_DELAY_TYPE_NONE
264endif
265
266config DEBUG_BOOT_PARAMS
267 bool "Debug boot parameters"
268 depends on DEBUG_KERNEL
269 depends on DEBUG_FS
270 ---help---
271 This option will cause struct boot_params to be exported via debugfs.
272
273config CPA_DEBUG
274 bool "CPA self-test code"
275 depends on DEBUG_KERNEL
276 ---help---
277 Do change_page_attr() self-tests every 30 seconds.
278
279config OPTIMIZE_INLINING
280 bool "Allow gcc to uninline functions marked 'inline'"
281 ---help---
282 This option determines if the kernel forces gcc to inline the functions
283 developers have marked 'inline'. Doing so takes away freedom from gcc to
284 do what it thinks is best, which is desirable for the gcc 3.x series of
285 compilers. The gcc 4.x series have a rewritten inlining algorithm and
286 enabling this option will generate a smaller kernel there. Hopefully
287 this algorithm is so good that allowing gcc 4.x and above to make the
288 decision will become the default in the future. Until then this option
289 is there to test gcc for this.
290
291 If unsure, say N.
292
293config DEBUG_ENTRY
294 bool "Debug low-level entry code"
295 depends on DEBUG_KERNEL
296 ---help---
297 This option enables sanity checks in x86's low-level entry code.
298 Some of these sanity checks may slow down kernel entries and
299 exits or otherwise impact performance.
300
301 If unsure, say N.
302
303config DEBUG_NMI_SELFTEST
304 bool "NMI Selftest"
305 depends on DEBUG_KERNEL && X86_LOCAL_APIC
306 ---help---
307 Enabling this option turns on a quick NMI selftest to verify
308 that the NMI behaves correctly.
309
310 This might help diagnose strange hangs that rely on NMI to
311 function properly.
312
313 If unsure, say N.
314
315config DEBUG_IMR_SELFTEST
316 bool "Isolated Memory Region self test"
317 default n
318 depends on INTEL_IMR
319 ---help---
320 This option enables automated sanity testing of the IMR code.
321 Some simple tests are run to verify IMR bounds checking, alignment
322 and overlapping. This option is really only useful if you are
323 debugging an IMR memory map or are modifying the IMR code and want to
324 test your changes.
325
326 If unsure say N here.
327
328config X86_DEBUG_FPU
329 bool "Debug the x86 FPU code"
330 depends on DEBUG_KERNEL
331 default y
332 ---help---
333 If this option is enabled then there will be extra sanity
334 checks and (boot time) debug printouts added to the kernel.
335 This debugging adds some small amount of runtime overhead
336 to the kernel.
337
338 If unsure, say N.
339
340config PUNIT_ATOM_DEBUG
341 tristate "ATOM Punit debug driver"
342 depends on PCI
343 select DEBUG_FS
344 select IOSF_MBI
345 ---help---
346 This is a debug driver, which gets the power states
347 of all Punit North Complex devices. The power states of
348 each device is exposed as part of the debugfs interface.
349 The current power state can be read from
350 /sys/kernel/debug/punit_atom/dev_power_state
351
352choice
353 prompt "Choose kernel unwinder"
354 default UNWINDER_ORC if X86_64
355 default UNWINDER_FRAME_POINTER if X86_32
356 ---help---
357 This determines which method will be used for unwinding kernel stack
358 traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack,
359 livepatch, lockdep, and more.
360
361config UNWINDER_ORC
362 bool "ORC unwinder"
363 depends on X86_64
364 select STACK_VALIDATION
365 ---help---
366 This option enables the ORC (Oops Rewind Capability) unwinder for
367 unwinding kernel stack traces. It uses a custom data format which is
368 a simplified version of the DWARF Call Frame Information standard.
369
370 This unwinder is more accurate across interrupt entry frames than the
371 frame pointer unwinder. It also enables a 5-10% performance
372 improvement across the entire kernel compared to frame pointers.
373
374 Enabling this option will increase the kernel's runtime memory usage
375 by roughly 2-4MB, depending on your kernel config.
376
377config UNWINDER_FRAME_POINTER
378 bool "Frame pointer unwinder"
379 select FRAME_POINTER
380 ---help---
381 This option enables the frame pointer unwinder for unwinding kernel
382 stack traces.
383
384 The unwinder itself is fast and it uses less RAM than the ORC
385 unwinder, but the kernel text size will grow by ~3% and the kernel's
386 overall performance will degrade by roughly 5-10%.
387
388 This option is recommended if you want to use the livepatch
389 consistency model, as this is currently the only way to get a
390 reliable stack trace (CONFIG_HAVE_RELIABLE_STACKTRACE).
391
392config UNWINDER_GUESS
393 bool "Guess unwinder"
394 depends on EXPERT
395 depends on !STACKDEPOT
396 ---help---
397 This option enables the "guess" unwinder for unwinding kernel stack
398 traces. It scans the stack and reports every kernel text address it
399 finds. Some of the addresses it reports may be incorrect.
400
401 While this option often produces false positives, it can still be
402 useful in many cases. Unlike the other unwinders, it has no runtime
403 overhead.
404
405endchoice
406
407config FRAME_POINTER
408 depends on !UNWINDER_ORC && !UNWINDER_GUESS
409 bool
410
411endmenu